Method of and apparatus for dry concentration



Jan. 9, 1940. G. w. BEACH 2,186,599

METHOD 0F AND APPARATUS FOR DRY CONCENTRATION Filed March 3, 1958 2 Sheets-Sheet 1 1N1 'ENTOR. 650265 114.3666

,-l TTORNEY.

Jan. 9, 1940.

G. W. BEACH METHOD OF AND APPARATUS FOR DRY CONCENTRATION Filed March 3, 1938 I 2 Sheets-Sheet 2 A TTORNEY.

Patented Jan. 9, 1 940;- if v i 1 METHOD OF AND APPARATUS FOR. DRY

, I CONCENTRATION George W. Beach; MinneapolisfMinnr Application March 3,1938, SerialNo'.'1 93,702

My invention relates .to a method of, and apparatus for, separating andrecovering precious and valuable metals such as gold, silver and the like from the. sand, gravel or soil in which-they are found in placer mining.

The primary object of the invention is to provide a method of separating valuable metals from the material in which vit is found which v employs air as the operating agent and whichin v 10. eludes the blowing of the air over rifles and discharging the material into the air -stream,-and which further includes the withdrawal of a part of the air back before it reaches the rifles and the subsequent return of this air into the main air stream Where it passes over the rifles to thus set up a turbulent, whirling'action which will cause the heavier particles to settle behind the rifles while the lighter material is blown out.

A further and most important object of the o invention is to provide an apparatus for this purpose in which the'deposit containing the gold or other metal is fed into the path of an air blast which carries the deposit over a series of rifles so that the heavier metal willcolle'ct behind: these rifles and the lighter material will be blown out and clear; and to provide 'also a' separate air chamber into which a part of theair blast is directed and subsequently'discharged downwardly into the main air blast to create the whirling, turbulent action over therifiies such'as will'cause the metallic particles to settlefbehind the rifles While the lighter particles of sand or soil will be blown outwardly from the machine thus leaving a concentrated collection of the valuable metal which may be removed and cleaned of any small impurities, if necessary, by washing; Another object is to provide a machine of thisk ind in which the rifles are arranged in a removable tray for convenient removal and cleaning and in which the rifles themselves are of serrated or saw-toothed design to facilitate their collecting action on the material blown thereover. A further object is to providev in a machine of this kind having a novel and efiect'iv'e feeding means for carrying the metal bearing deposit into the path of the air blast and which 'is so designed as to prevent clogging or over-feeding of the material and insure even distributionjof the material over the entire rifle assembly; 'A'further object 7 Claims. (61. 20947?) ily. accommodate the machine to use in material of any-character. f Still a further'important object isto provide a machine for this purpose in a simple, compact and portable form and which employs no working 5 parts other than the blower and prime mover which providethe air blast for the operation of the machine. 1

The foregoing and other more detailed objects of the invention, together with means whereby 10 I they may be carried into effect, will best be understood. from the following specification in which reference is madev to the accompanying drawings, wherein: I

- Figure 1 is a side elevation of the complete ma- 15;.

chine as set up ready for use. 1

Figure 2 is an enlarged vertical and longitu dinal-section through the machine proper, only] a portion or" the feed hopper and the air blower beingshown. 1 I I Figureii'is a plan-view of the structure shown in'Figure 2, a portion of the'machine being broken away to disclose interior construction.

' Figure '4 is a fragmental horizontalsection along the line 4-4 in Figure 2. U w

Figure 5' is a vertical cross section"v along the line 5-5 inFigure'Z. i I

'Referring now with more particularity to the drawings, my invention is seen to! comprise two- 'main units, the'apparatus; or machine A andthe 0 power unit 13;

The apparatus A comprisesthe'riffle housing 6 which" constitutes the ,base member or the 'ma'J-j china and which is" arranged 'for removable mounting in a base-frame orvstancl I; made up 3.5 of legs 8 andbr'aces 9 which support the machine at a convenient working height from the'groun'd; The extended upperends 8a of the legs 8 define crotches or'seats for the reception of the rifle housing 6.' This-housingfiis', as'show'rnof elori-. "-4 gated fiat form made up of sheet metal to provide the bottom lfil; narrow vupsta'riding'sides or margins l I andthe top l2 allof which define and enclose the rifle chamber 13. The ends of this chamber are open as shown at M -andl5 and the end l4 ishereinafter known as the intake end and the end [5 asthe discharge or delivery end. Sui-mounting the housing 6 is the upper air chamber housing, It which extends from adjacent the-intake end I4 over the greater part of the length of" housing 6,;this housing l6 having thevside walls l1} the'ends l8-and l9 and'the't'op or cover- 20 which 1 define and enclose an air chamber 2|. This chamber 2| is considerably, 56

through the housing top 20 in transverse spac- 1 ing within the hopper receptacle 22 and these tubes open at their upper ends, as at 21, so that the material fed from the hopper will enter the tubes. The feed may, however, be cutoff to any tube and at any time by means of slidable cutoff valves 28 which lie fiat on the housing top 20 and pass slidably through slots 29 in the wall 23 so that they may be moved inwardly'over the mouths of the tubes. From their upper ends the tubes 26 incline downwardly and forwardly (away from the intake end of the machine) and drop through openings formedin the top E2 of the rifiiehousing-.5 to thereby enter the riflie chamber 13 at a point spaced some distance from the intake end I4 thereof. The lower extremities of the feed tubes 26 are out ofi angularlyas at 30 to stand parallel to, but spaced some distance from, the housing bottom it.

The ritfie assembly or unit, designated generally at 31, comprises a tray or pan 32 of elongated rectilinear form adapted to be slipped. endwise (through the delivery end 15) into the riflle chamber l3; This tray 32 has its lateral margins 33 turned upwardlyto serve as guides and hold the tray in position in chamber l3 and the length and Width is such that the, tray will fit nicely into, the, chamber, with one end slipped beneath the lower extremities of the feed tubes 26 and the other end extended, some distance outwardlyof the delivery e1,1d of the chamber to provide a hand hold for removing and replacing the tray. Spaced along the length of the tray 32 are a plurality of transversely extended rifiles, rifile bars or cleats 34 which are inclined upwardly from the vertical in a direction away from the intake end 14 of the chamber 13. These rifles 34 are welded or otherwise secured in the tray'32, are of substantially less height than the chamber I3 and are serrated or saw-toothed along their-"upper margins as shown at 35. The function of these ifiiiles and the advantagesarising from their serrated construction will be hereinaftermore fully set forth.

It will be noted that, with the riflie tray 32 in place, the lower or delivery ends of the feed tubes 26 clear the tray but a very slight distance and to permit the material from the hopper to feed down to the tray the frontal sides, or the sides remote from the intake end M of the chamber l3, are out out from diametrically opposite points up to about thelevel of the upper wall of the chamber 13 as indicated at 36.

The machine as herein shown and described embodies three feed tubes but it is to be understood that the machine may be made in any width, either greater or less, and may employ a corresponding number of the tubes. At points medially locatedbetween adjacent feed tubes the cover l2 or the riffle housing 6 is provided with air inlets or inlet openings 31 which are disposed inwardly of the adjacent end [8 of the housing l5 but immediately adjacent the intake end I4 .ofthe chamber 13. Beneath each of these inlets 31 an inlet valve 38, of the so-called flap type, is located and is hinged at 3811 to the underside of the cover l2 so that the free end of the valve may swing downwardly into the chamber l3 toward the intake end 14 thereof. A long screw 39 is pivotally attached at 3901. to each valve 38 and extends upwardly through the housing cover 29 where it is provided with a wing nut 40 to thereby allow the valve to be adjusted in its position relative to its associated inlet 31. Therefore, when the wing nuts 40 are turned down on the screws 39, the valves 38 may be pulled upward to close the inlets 38, and vice versa. Normally the valves will stand'slightly opened as shown in the drawings and Will stand in adjusted position by force of gravity.

Forwardly of the feed tubes 26, or toward the delivery end of the machine, the housing cover l2 has several sets of parallel transverse rows of airreturn openings or apertures 41 and over each set or pair of these rows of openings an air return regulator or damper 42 is provided. These dampers 42, here shown as three in number, are attached at one margin to hinge rods 43 which extend through the'sides I! of the housing Hi immediately above the level of the cover l2 to pivotally support the dampers so that their free edges turn back toward the intake end of the machine. The dampers are of rectangular, fiat shape of such length as to fit nicely between the housing side i! and of such width that, in one position, theywill close the adjacent air return openings 4! and, in another, they will stand upwardly against the housing top 20 to form a partition or air stop at that point. This positioning of the dampers 42 is carried out by means of handles 44 which are turned at right angles from one end of the rods 43 and play over the side of the housing It in engagement with toothed quadrants or racks 45 secured to said sides. Normally then dampers 42 will, like the valve 38, stand open to some degree as shown.

The foregoing assembly completes the machine itself and the power unit B will now be described. This comprises the base 45 supported on legs 41 and carrying a conventional form of air blower 48 having its outlet hood 49flared to provide a wide mouth 50 of such shape that it may slidably enter the intake end M of the rifile chamber 13. The base 46 is supportedat such height that it will allow the hood 49 to engage the machine A as described. A prime mover 5! of any kind is mounted also on the base 46 and drives the blower 48 through the belt 52 or equivalent means. Of course the type of prime mover used will depend upon the fuel or power available but, inasmuch as the machine will ordinarily be employed in relatively remote locations it is probable that a small gasoline engine will be employed as shown. In such case a pipe, such as 53, may be led from the engine exhaust to'the blower intake in order that the air emitted from the blower 48 will be heated and will serve to dry out the materials fed tothe machine A where such action is. necessary.

The delivery end or mouth 50 of the blower hood 49 has air guides or fins 54 of V-shaped form located in line with the valves 38. The pure pose of these guides 54 is to direct the air blast from the blowers directly against the feed tubes 26 .as will be evident and to thus distribute the feed evenly over the rifile tray. The guides 54 are Welded at their bights 55 within the hood 49 but their wings 56 are left free so that they may.

fit entersthe feed tubes down into the rifiie chamber 13 and discharged be compressed or spread apart as may be required 'toproperly adjust the air distribution.

In operation the gravel or soil to be worked is, if necessary, screened to remove the larger pieces and then with the blower 48 in operation, the material is placed in the hopper 2-4 so that 26 and is carried thereby onto the riflie tray 32. It will'immediatelybe apparent that the blast of air entering the chamber I3 through its 'intake'end 14 will blow the material forwardly over the riflle tray and the 'rifiles 34 thereon and will spread the material evenly from the feed tubes 26 over the entire width of the tray. This action results from the novel arrangement of the delivery ends of the tubes 26 wherein the cut outs 36, located remote from the entrance of the air blast, allows the air to spread the materialforwardly and'laterally as it emerges from the tubes. Overfeeding and v clogging is thus prevented and the location of the ends 38 of the tubes 26 immediately adjacent the rifile tray 3-2 presents-an overhang or shield I such as will prevent the material from being "blown up the tubes by the-air. v

At the same time as the material 'is being blown forwardly overthearifiies 34a part of the air from the blower 48 is being deflected by the open valves 38 upwardly through the inlets 31 into the air chamber 2|, and this air is then returned to the riflle chamber [3 at intervals along the length thereof through the air return open This air returning into the main air to the direction of travel ings 4|. stream at an angle thereof sets up .a turbulent, swirling or whirling motion over the riffles 34 resulting in a like action on the part of the material such as will allow the particles of gold or other metal (which are heavier than the material itself) to settle-behind the riflies 34 where they are protectedfrom the air blast. The lighter material, finally is blown out the discharge end 15 of the housing 6. This action is continuous so long as the blower operatesand the material is fed to the hopper but the action may be stopped at any time by .shutting off the blower and closing the slide valves 28.

As shown in the drawings the rifile housing 6, air chamber housing I6 and the rifiie tray 32 taper somewhat in width and in a longitudinal direc-'' tion and are accordingly somewhat narrower at the intake end of the apparatus. Thisformation has. a twofold purpose. In the first place the material as it is spreadby the air blast toward the discharge ,end of the machine has more space in which to move and the riflles themselves are longer so that the'fiow of material is sub- 7 stantiallyruniform over the entire area of the riflie assembly. Another advantage in this tapering arises from the ease with which the rifile tray 32 may be inserted into the rifile chamber l3 to provide a tight fit such as will prevent any of the material from working down beneath the tray. 7

Thewhirling, turbulent motion given the material by the returning of a part of the initial air blast to the main air stream over the riflles is an extremely important feature in that it allows much more of the finer metal to settle behind the riffles thanwould be the case where the air stream blown straight over the riffles. It is also important that the amount of air thus returned and used be regulated, at least roughly,

according to the nature and quality of the mate may be required. I

The machine or apparatus thus is seen to'permit the practice of an entirely new and effioacious method of separating the heavier valuable metal from the material in which it is found, tl'iis method comprising blowing an air blast'over riffles, feeding the material into the air blast, diverting a part of the air before it reaches the feeding means and subsequently returning this air to the main air stream over the riflles to thereby set up a turbulent swirling effect on the air and materials. e

An important and advantageous feature of my invention lies in the fact that the method and the apparatus, using air as' the agitating agent, may be used in many arid locations where the wet-methods and washers cannot be used. Another advantage is the ease with which the apparatus, at least in the .small size herein shown, may be taken down, carried from place to'place and set up for operation at a new location. p

The material collected behind the riflies'34 may be removedand, if necessary,- further cleaned by washing; this action being readily carried out by removing the riflietray 32. The serrated upper margins 35 of the riflies permit the use of wider or I higher riflles without undulyobstructing the separating action of the material and thus affords considerably greater effective area or surface for the riflles.

While I have herein set forth; a certain preferred embodiment of my invention, it is under- 'stood that I may vary from the same in minor details, so long as such variations fall within the spirit and scope of the appended claims.

Having thus fully disclosed my invention, what meeting the deposit and subsequently returningthis diverted air downwardly to the main air stream to thereby set up a turbulence in the air stream carrying the deposit over the rifiles.

2. The method of separating valuable minerals from the natural deposit in which they are found,

which comprises feeding the deposit onto a rifile surface, blowing an airstream over the riffle surface and in a direction crossing the rifiles, diverting air from the air stream before it reaches the deposit and subsequently returning this diverted air downwardly to-the air stream at an angle to the direction of travel thereof to thereby set up a turbulence in the air over the riflie surface.

.3; The method of agitating a natural deposit over a rifile surface to separate valuable metals therefrom, which comprises feeding the deposit adjacent the riflie surface, blowing an air stream across the rifiie surface to carry the deposit there- "over, and directing air downwardly into the path of this air stream over the riiile surface to cause a turbulence in the air stream.

4. An apparatus for separating valuable metals from a natural deposit, comprising a housing having a chamber open at its opposite ends, means for directing an air stream through the chamber from end to end thereof, rifiie members located in the chamber transversely to the path of the air therethrough, deposit feeding devices entering the chamber adjacent the end at which the air stream enters, and an inlet meansspaced along the length of the chamber over the rifile devices in parallelism therewith and effective'to the riflie chamber but closed at its ends, an air supply means connected to one end of the rifile chamber to direct an air stream therethrough,

an air inlet connecting the chambers adjacent ,this end of the riffle chamber, an air valve adjacent the said inlet and adjustable to divert a part of the air, stream into the air chamber, feeding devices enterin the little chamber inwardly of the said inlet, air return means con.-

necting the chambers and spaced along the length and overhead of the riflie chamber, dampers arranged over the said air return means,.and a riffle assembly mounted in the rifiie chamber.

6. An apparatus for separating valuable metals from a natural deposit, comprising ahcusing having a riflie chamber open at'its ends, and an air chamber over the riflie chamber, means for feeding an air stream to one end of the riffie chamber, an air inlet connecting the two chambers adjacent this end, a flap valve arranged over the air inlet and adjustable into the pathof the air stream entering the riflle chamber to thereby .divert air into, the air chamber,-the said housing also having air return openings spaced along the length of the air chamber and communicating with the rifiie chamber, damper plates adjustable over the said air return openings and adapted to divert air from the air chamber into the rifile chamber, deposit feeding means entering the riffle chamber between the said air inlet and the air return openings, and rifile devices in the riffie chamber.

'7. An apparatus for separating valuable-metals from a natural deposit comprising a rifile chamber open at opposite ends, blower means fordirecting ,20

an air stream endWise-through the riffie chamber, feed means for feeding the deposit into the path of the air stream, rifiie means in the bottom of the riffle chamber and opening upwardly and angularly in the direction of the air stream, and

means for directing diverted air streams downwardly into the main air stream and toward the riflie means.

GEORGE W. BEACH. 

